Magistrate Gadiel Mariki passed sentence on Tuesday on the trio after finding them guilty of 'forcing a girl to have sex with a dog' in the northern city of Mwanza in March 2008, an official told AFP by phone from the Lake Victoria city.
Job Mlama, 30, Anicet Edward, 30, and Shija Madata, 18, were employed by Canadian mining exploration company, Barrick Exploration Africa Limited (BEAL) at Mwanza, some 800 kilometres north of the capital Dar es Salaam.
They were sacked from their jobs shortly after the incident.
In his judgement, Judge Mariki said the trio lured the schoolgirl into the BEAL workers' campsite, and convinced her to spend the night there before forcing her into bestiality.
The court ordered that the dog, owned by one of the expatriates at BEAL, be turned over to the police, Human rights activists condemned the sentence as too lenient.
'These people deserved the death penalty or a life term. It is a horrible, despicable offence,' said Ichikaeli Maro, the former head of a women's rights group.
'They deserved a punishment that should be a lesson to others with such a habit,' said Rehema Kerefu, director of the Tanzania Women's Legal Aid Committee. -- AFP